Valmiki Ramayana Kishkindha Kanda Sarga 56 Shloka 15

कैकेय्याः to Kaikeyi, वरदानेन the granting of boons, सीतया सह along with Sita, अरण्ये in the forest, रामलक्ष्मणयोः of Rama and Lakshmana, वासः residence, तथा so also, राघवस्य Rama's, बाणेन with arrow, वालिनः Vali's, वधश्च death, तथा so also, रामकोपात् due to Rama's anger, अशेषाणाम् of the entire lot, रक्षसानाम् demons, वधश्च death, इदम् this, विकृतं च unwanted consequence, कृतम् was done.

'The exile of Rama and Lakshmana into the forest along with Sita, so also the death of Vali and of the demons in the hands of Rama due to his anger are all evil consequences of a boon granted to Kaikeyi.'